WO2019069648A1

WO2019069648A1 - Vision examination device

Info

Publication number: WO2019069648A1
Application number: PCT/JP2018/033824
Authority: WO
Inventors: 安井賢治; 鈴木誠; 菅原充; 長谷川欣也
Original assignee: 株式会社Ｑｄレーザ
Priority date: 2017-10-05
Filing date: 2018-09-12
Publication date: 2019-04-11
Also published as: US11717157B2; CN111163682A; EP3692889A4; JP6677859B2; EP3692889B1; EP3692889A1; JP2020099736A; CN111163682B; US20200229694A1; JPWO2019069648A1

Abstract

A vision examination device comprising: a light source 11 that emits a visible laser light 50a and an infrared laser light 50b; an image projection optical system 14 that has a scanning unit 20 oscillating at a first frequency to scan the visible laser light 50a in two dimensions, and that shines the visible laser light 50a onto a subject's retina 74 to project an image onto the subject's retina 74; an infrared light optical system 15 that has a scanning unit 22 oscillating at a second frequency, which differs from the first frequency, to scan the infrared laser light 50b in two dimensions, and that shines the infrared laser light 50b onto the subject's retina 74; a detector 40 that detects the infrared laser light 50b reflected by the subject's retina 74; and a control unit 30 that controls the emission of the visible laser light 50a and the infrared laser light 50b from the light source 11, and detects a condition of the subject's ocular fundus from an output signal of the detector 40.

Description

Visual inspection device

The present invention relates to a visual inspection apparatus.

A fundus examination with a scanning laser ophthalmoscope (SLO: Scanning Laser Ophthalmoscope) is known. There is also known an ophthalmologic apparatus provided with a function of scanning laser ophthalmoscope and a function of visual field measurement (e.g., Patent Document 1).

JP 2007-181537 A

In an examination apparatus capable of projecting an image on the retina in addition to irradiating invisible light for examination of the eye to the retina of the subject, the image is displayed using a liquid crystal display as in Patent Document 1 In some cases it is difficult to project high resolution images.

The present invention has been made in view of the above problems, and an object thereof is to provide a visual inspection apparatus capable of projecting a high resolution image.

The present invention has a light source for emitting visible light and invisible light, and a first scanning unit for two-dimensionally scanning the visible light by oscillating at a first frequency, and the visible light is transmitted to the retina of the subject And an image projection optical system that projects an image onto the retina of the subject, and a second scanning unit that two-dimensionally scans the invisible light beam by oscillating at a second frequency different from the first frequency. An invisible light optical system for irradiating the invisible light to the subject's retina, a detector for detecting the invisible light reflected by the subject's retina, the visible light from the light source and the invisible light And a control unit configured to control emission of a light beam and to detect a state of a fundus of the subject from an output signal of the detector.

In the above-described configuration, the image display optical system and the invisible light may further include a light splitting unit that emits the visible light emitted from the light source in a first direction and emits the invisible light in a second direction different from the first direction. The optical axis with the optical optical system is coincident, and the image projection optical system two-dimensionally scans the visible light emitted in the first direction and irradiates the retina of the subject with the invisible light. The optical optical system may be configured to two-dimensionally scan the invisible light emitted in the second direction and to irradiate the retina of the subject.

In the above configuration, the light separating unit may be a dichroic mirror that transmits one of the visible light and the invisible light and reflects the other.

In the above configuration, the image processing apparatus may further include a combining unit configured to combine the visible light scanned by the first scanning unit and the invisible light scanned by the second scanning unit.

In the above configuration, the invisible light beam may be an infrared light beam, and the control unit may be configured to generate a fundus image of the eye of the subject based on an output signal of the detector.

In the above configuration, the control unit controls the emission of the visible light from the light source to project a fixation target for causing the line of sight of the subject to be directed to the retina of the subject, and the light source The invisible light beam may be emitted from the light source to illuminate the invisible light beam on the retina of the subject.

In the above configuration, the control unit may be configured to control an emission of the visible light from the light source to project a test target for testing the eye of the subject on the retina of the subject. Can.

In the above configuration, the control unit controls emission of the visible light from the light source to project a test target for testing the eye of the subject on the retina of the subject, and the light source. And the irradiation of the invisible light to the retina of the subject can be performed in parallel.

In the above configuration, the control unit controls the emission of the visible light from the light source to project a test target for testing the eye of the subject on the retina of the subject, and the detector A third inspection image in which a first inspection image generated based on an output signal of the second inspection image and a second inspection image generated based on a response input according to the inspection target of the subject are superimposed can do.

In the above configuration, the first examination image may be a fundus image, and the second examination image may be an image regarding a visual field defect.

The present invention has a light source for emitting visible light and invisible light, and a first scanning unit for two-dimensionally scanning the visible light by oscillating at a first frequency, and the visible light is transmitted to the retina of the subject And an image projection optical system that projects an image onto the retina of the subject, and a second scanning unit that two-dimensionally scans the invisible light beam by oscillating at a second frequency different from the first frequency. An invisible light optical system for irradiating the invisible light to the subject's retina, a detector for detecting the visible light and the invisible light reflected by the subject's retina, and the light source from the light source Control of emission of visible light and the invisible light, detection of the state of the first fundus of the subject from the output signal based on the visible light of the detector, and output signal based on the invisible light of the detector From the second fundus of the subject A control unit for the detection of states, a visual inspection device comprising a.

In the above configuration, the control unit controls the emission of the visible light from the light source to cause the gaze of the subject to be directed to the retina of the subject, and the subject It is possible to project at least one of the examination targets for examining the eye of the subject.

In the above configuration, the control unit may be configured to generate a fundus image of the eye of the subject as the detection of the state of the first fundus and the detection of the state of the second fundus.

The present invention comprises a visible light source for emitting visible light, an invisible light source for emitting invisible light, a light source light combining unit for combining the visible light and the invisible light to generate combined light, and the visible light A scanning unit for two-dimensionally scanning the invisible light beam, and the visible light beam irradiated to the retina of the subject to project an image on the retina of the subject, and the invisible light beam to the retina of the subject An emission optical system for irradiating, a detector for detecting the invisible light reflected by the retina of the subject, and control of emission of the visible light from the visible light source and the invisible light from the invisible light source And a control unit that detects the state of the fundus of the subject from the output signal of the detector.

In the above configuration, the control unit controls the emission of the visible light from the visible light source to project a fixation target for causing the subject's line of sight to be directed to the retina of the subject. The invisible light beam may be emitted from the invisible light source to irradiate the retina of the subject with the invisible light beam.

In the above configuration, the control unit may control emission of the visible light from the visible light source to project a test target for testing the eye of the subject on the retina of the subject. can do.

In the above configuration, the control unit controls the emission of the visible light from the visible light source to project a test target for testing the eye of the subject on the retina of the subject, A third inspection image is generated by superimposing the first inspection image generated based on the output signal of the detector and the second inspection image generated based on the response inputted according to the test target of the subject. It can be configured.

According to the present invention, a high resolution image can be projected.

FIG. 1 is a block diagram of a visual inspection apparatus according to a first embodiment. FIG. 2 is a diagram illustrating an optical system of the visual inspection apparatus according to the first embodiment. FIGS. 3A and 3B are diagrams for explaining scanning of visible laser light and infrared laser light. FIG. 4 is a flowchart showing the process in the first embodiment. FIG. 5 is an example of a fundus oculi image generated by the image generation unit. FIG. 6 is a block diagram of a visual inspection apparatus according to a second embodiment. FIG. 7 is an example of an image projected onto the retina in the second embodiment. FIG. 8 is a flowchart showing processing in the second embodiment. FIG. 9 is a flowchart showing a method of examination using the examination target in the second embodiment. 10 (a) to 10 (d) are diagrams for explaining an examination using an examination target. FIGS. 11A to 11C are examples of the fundus image, the visual field defect image, and the superimposed image generated by the image generation unit. FIGS. 12 (a) and 12 (b) are other examples of images projected onto the retina in Example 2. FIG. FIG. 13 is a flowchart showing the process in the third embodiment. FIG. 14 is a block diagram of a visual inspection apparatus according to a fourth embodiment. FIG. 15 is a diagram of an optical system of a visual inspection apparatus according to a fourth embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a visual inspection apparatus according to a first embodiment. As illustrated in FIG. 1, the visual inspection apparatus 100 according to the first embodiment includes a projection unit 10, a control unit 30, a detector 40, and a display unit 41. The projection unit 10 includes a light source 11, an adjustment unit 12, a spectroscopy unit 13, an image projection optical system 14, an infrared light optical system 15, a drive circuit 16, and an input circuit 17. The image projection optical system 14 has a scanning unit 20, and the infrared light optical system 15 has a scanning unit 22. The scanning units 20 and 22 (scanners) are, for example, scanning mirrors such as MEMS (Micro Electro Mechanical System) mirrors or transmission type scanners. The control unit 30 includes a drive control unit 31, a signal processing unit 32, and an image generation unit 33.

The drive control unit 31 generates an image to be projected on the retina. An image signal from the drive control unit 31 is input to the input circuit 17. The drive circuit 16 drives the light source 11 and the

scan units

20 and 22 based on the image signal acquired by the input circuit 17 and the control signal of the drive control unit 31.

The light source 11 includes, for example, visible light of red laser light (wavelength: about 610 nm to about 660 nm), green laser light (wavelength: about 515 nm to about 540 nm), and blue laser light (wavelength: about 440 nm to about 480 nm) The invisible light beam (wavelength: about 850 nm) is emitted. That is, the light source 11 has laser diode chips for red laser light, green laser light, blue laser light, and infrared laser light in one module. The light source 11 may emit laser light of a single wavelength as visible light.

The adjustment unit 12 includes a collimator lens, a toric lens, and / or an aperture, and shapes the laser beam 50 emitted from the light source 11. The laser beam 50 is a light beam in which a red laser beam, a green laser beam, a blue laser beam, and / or an infrared laser beam are combined, and the optical axes of the respective laser beams coincide with each other. The spectral unit 13 is, for example, a dichroic mirror, and divides the laser light 50 into visible laser light 50a of red laser light, green laser light, and blue laser light, and infrared laser light 50b. The image projection optical system 14 two-dimensionally scans the visible laser light 50 a separated by the light separating unit 13 by the scanning unit 20 and irradiates the eye 70 of the subject. The infrared light optical system 15 two-dimensionally scans the infrared laser light 50b separated by the light separating unit 13 by the scanning unit 22 and irradiates it to the eye 70 of the subject, for example, a conventional scanning type It implements some of the functions of the laser ophthalmoscope (SLO).

The detector 40 is, for example, a photodetector such as an avalanche photodiode, and detects the infrared laser light 50b reflected by the eye 70 of the subject. The signal processing unit 32 processes the output signal of the detector 40 based on the control signal from the drive control unit 31. The image generation unit 33 generates a two-dimensional image based on the signal processed by the signal processing unit 32. The display unit 41 is, for example, a liquid crystal display, and displays an image generated by the image generation unit 33. The detector 40 and the signal processing unit 32 start detection based on the synchronization signal from the drive circuit 16 at the timing when the light source 11 emits the infrared laser light 50 b.

For example, in the drive control unit 31, the signal processing unit 32, and the image generation unit 33, a processor such as a central processing unit (CPU) may perform processing in cooperation with a program. The drive control unit 31, the signal processing unit 32, and the image generation unit 33 may be circuits designed for exclusive use. The drive control unit 31, the signal processing unit 32, and the image generation unit 33 may be one circuit or different circuits.

FIG. 2 is a diagram illustrating an optical system of the visual inspection apparatus according to the first embodiment. As illustrated in FIG. 2, the visual inspection apparatus 100 according to the first embodiment irradiates laser light to the retina 74 of the subject using Maxwell vision. The numerical aperture (NA) and / or the beam diameter of the laser light 50 emitted from the light source 11 is adjusted by the adjustment unit 12. The laser beam 50 is split into the visible laser beam 50a of the red laser beam, the green laser beam, and the blue laser beam, and the infrared laser beam 50b in the beam splitting unit 13. The spectral unit 13 is, for example, a dichroic mirror that transmits the visible laser light 50 a and reflects the infrared laser light 50 b. The light separating unit 13 is not limited to a dichroic mirror, and may be another optical element such as a dichroic prism.

The visible laser beam 50 a is reflected by the flat mirror 21 and scanned two-dimensionally by the scanning unit 20. The scanned visible laser light 50 a is irradiated to the eye 70 of the subject via the lens 25, the combining unit 26, and the lens 27. The visible laser light 50 a converges near the lens 72, passes through the vitreous body 76, and irradiates the retina 74. Thus, an image is projected on the retina 74. The scanning unit 20 vibrates at a relatively high frequency such as 28 kHz, for example, so that an image of 60 frames is projected per second.

The infrared laser beam 50 b is reflected by the flat mirror 23 and is two-dimensionally scanned by the scanning unit 22. The scanned infrared laser light 50 b is applied to the eye 70 of the subject via the lens 24, the combining unit 26, and the lens 27. The infrared laser light 50 b converges near the lens 72, passes through the vitreous body 76, and irradiates the retina 74. The infrared laser light 50 b is reflected by the retina 74. The reflected infrared laser light 50 b returns in the optical path along which the infrared laser light 50 b has traveled toward the retina 74. That is, the reflected infrared laser beam 50 b is an optical path in which the infrared laser beam 50 b has traveled toward the retina 74 in the order of the lens 27, the combining unit 26, the lens 24, the scanning unit 22, the plane mirror 23, and the light separating unit 13. , And enters the detector 40 via the half mirror 43 and the lens 44. Thereby, the detector 40 detects the infrared laser light 50b reflected by the retina 74. Detection of the state of the fundus of the eye 70 (acquisition of state information of the fundus) can be performed according to the detection result of the luminance change of the infrared laser light 50b by the detector 40, and a fundus image is acquired as an example of the detection target can do. The scanning unit 22 is relatively low such as 12.5 kHz, which corresponds to the case where an image of 25 frames is projected, for example, so that detection of the state of the fundus of the eye 70 can be realized by the infrared laser light 50b. It vibrates at a frequency.

FIG. 3A and FIG. 3B are diagrams for explaining the scanning of the visible laser beam 50a and the infrared laser beam 50b. As shown in FIG. 3A, the image 60 is projected onto the retina 74 by the visible laser beam 50a. The scanning unit 20 of the image projection optical system 14 raster scans the visible laser light 50 a from the upper left to the lower right as shown by the arrow 61. Even if the scanning unit 20 vibrates, the visible laser light 50a is not irradiated to the retina 74 unless the light source 11 emits the visible laser light 50a. The visible laser beam 50a is not emitted at the dashed arrow 61 in FIG. 3A. The drive circuit 16 synchronizes the emission of the visible laser light 50 a from the light source 11 and the vibration of the scanning unit 20. Thereby, the light source 11 emits the visible laser light 50 a in the thick solid line 62. As a result, for example, a fixation target 63 for projecting the line of sight of the subject to a central region of the retina 74 is projected. The fixation target 63 is not limited to the cross pattern, and may be any other figure as long as the line of sight of the subject can be directed, such as a dot pattern, a star pattern, a circular pattern, or a polygonal pattern. . Further, the display position of the fixation target 63 is not limited to the central region of the retina 74, and may be appropriately changed as needed.

As shown in FIG. 3B, the scanning unit 22 of the infrared light optical system 15 raster scans the infrared laser light 50b from the upper left to the lower right as indicated by the arrow 64. If the light source 11 does not emit the infrared laser beam 50b even if the scanning unit 22 vibrates, the infrared laser beam 50b is not irradiated to the retina 74. The drive circuit 16 synchronizes the emission of the infrared laser light 50 b from the light source 11 and the vibration of the scanning unit 22. Even when the infrared laser beam 50b is irradiated to the retina 74, the infrared laser beam 50b is an invisible ray, so the subject can not recognize that the infrared laser beam 50b is irradiated. The light source 11 emits the infrared laser light 50 b in, for example, substantially the same range as the image 60 in the vibration of the scanning unit 22.

Returning to FIG. 2, the scanning angle of the visible laser light 50a by the scanning unit 20 and the scanning angle of the infrared laser light 50b by the scanning unit 22 are, for example, substantially the same size. The combining unit 26 is, for example, a dichroic mirror, and combines the visible laser beam 50 a scanned by the scanning unit 20 and the infrared laser beam 50 b scanned by the scanning unit 22. The optical axes of the visible laser light 50a and the infrared laser light 50b after being combined by the combining unit 26 coincide with each other. The combining unit 26 is not limited to a dichroic mirror, but may be another optical element such as a dichroic prism.

The image projection optical system 14 includes a scanning unit 20, a plane mirror 21, a lens 25, a combining unit 26, and a lens 27. The infrared light optical system 15 includes a scanning unit 22, a plane mirror 23, a lens 24, a combining unit 26, and a lens 27. The combining unit 26 and the lens 27 are components common to the image projection optical system 14 and the infrared light optical system 15.

FIG. 4 is a flowchart showing the process in the first embodiment. As illustrated in FIG. 4, the drive control unit 31 generates an image 60 as illustrated in FIG. 3A, causes the projection unit 10 to project the generated image 60, and causes the retina 74 to project the fixation target 63. (Step S10). Next, as shown in FIG. 3B, the drive control unit 31 causes the projection unit 10 to irradiate the retina 74 with the infrared laser light 50b (step S12).

Next, the signal processing unit 32 acquires an output signal of the detector 40 (step S14). For example, the detector 40 detects the infrared laser light 50 b in synchronization with the synchronization signal from the drive circuit 16. That is, the detector 40 detects the infrared laser light 50 b in synchronization with the emission of the infrared laser light 50 b from the light source 11. The signal processing unit 32 starts acquiring the output signal of the detector 40 in synchronization with the emission of the infrared laser light 50 b.

Next, the drive control unit 31 determines whether or not the irradiation of the infrared laser light 50b has ended in a predetermined number of frames (step S16). The predetermined number of frames may be one frame or a plurality of frames such as five or ten frames. The number of frames suitable for detecting the state of the fundus of the eye 70 may be appropriately selected by irradiating the retina 74 with the infrared laser light 50 b.

When the irradiation of the infrared laser light 50b of the predetermined number of frames is not completed (step S16: No), steps S12 and S14 are repeated. When the irradiation of the infrared laser light 50b of the predetermined number of frames is completed (Step S16: Yes), the drive control unit 31 causes the projection unit 10 to end the projection of the fixation target 63 (Step S18).

Next, the image generation unit 33 generates an inspection image (for example, a fundus image) of the eye 70 based on the output signal of the detector 40 acquired by the signal processing unit 32 (step S20). When the infrared laser light 50b is irradiated in a plurality of frames, the image generation unit 33 may obtain an average value of the output signals of the detector 40 in each of the plurality of frames to generate an inspection image, or The inspection image may be generated by the maximum value. The display unit 41 displays an examination image (step S22). The examiner examines the vision of the subject by the examiner examining the examination image indicating the state of the fundus displayed on the display unit 41. In addition, as a detection of the state of the fundus, it is also possible to detect an uneven tumor, a pseudo three-dimensional image using a phase difference, or opacity of the vitreous body.

FIG. 5 is an example of a fundus oculi image generated by the image generation unit. In FIG. 5, reference numeral 80 is a fovea, reference numeral 81 is an optic nerve head, and reference numeral 82 is a retinal artery or retinal vein. The lesion 83 is shown by the cross hatch.

In the first embodiment, as shown in FIG. 4, while projecting the fixation target 63 onto the retina 74 of the subject, the retina 74 is irradiated with the infrared laser light 50b. As a result, since it becomes possible to obtain an examination image showing the state of the fundus in a state in which the subject directs his / her gaze at the fixation target 63, it is possible to obtain a stable examination image with good reproducibility. Thus, in addition to the irradiation of the retina 74 with the infrared laser light 50b for acquiring the examination image showing the state of the fundus of the eye 70, it is preferable that the image can be projected on the retina 74. When a display is used, it is difficult to project a high resolution image on a predetermined position of the retina 74.

Therefore, in the first embodiment, as shown in FIGS. 1 and 2, the image is projected on the retina 74 by irradiating the retina 74 with the visible laser light 50 a scanned by the scanning unit 20 two-dimensionally. Thereby, a high resolution image can be projected. At this time, it is desirable that the scanning unit 20 that scans the visible laser light 50a vibrate at about 28 kHz so that an image of 60 frames is projected, for example, per second. On the other hand, the condition of the fundus of the subject is detected from the output signal of the detector 40 that irradiates the retina 74 with the infrared laser light 50b scanned in a two-dimensional manner by the scanning unit 22 and detects the reflected light at the retina 74. When this is done, it is desirable that the scanning unit 22 vibrate at about 12.5 kHz, which corresponds to, for example, the case where an image of 25 frames is projected per second. This is due to the processing convenience such as the accuracy when using the infrared laser light 50b. In the first embodiment, since the scanning unit 20 for scanning the visible laser beam 50a and the scanning unit 22 for scanning the infrared laser beam 50b are separately provided, they can be oscillated at different frequencies, and the above-mentioned demands are realized. it can. In addition, by projecting the image by irradiating the retina 74 with the visible laser light 50a scanned in a two-dimensional manner by the scanning unit 20, the inspection apparatus can be made smaller than when the image is projected using a liquid crystal display. it can. The

scanning units

20 and 22 are preferably two-axis MEMS mirrors in terms of downsizing, weight reduction, and cost reduction of the inspection apparatus.

Further, according to the first embodiment, as shown in FIG. 2, the visible laser light 50a emitted from the light source 11 is emitted in the first direction, and the infrared laser light 50b is emitted in the second direction different from the first direction. The spectroscope unit 13 is provided. The optical axes of the image projection optical system 14 and the infrared light optical system 15 coincide with each other, and the image projection optical system 14 two-dimensionally scans the visible laser light 50a emitted in the first direction by the spectroscope unit 13 The infrared light optical system 15 two-dimensionally scans the infrared laser light 50 b emitted in the second direction by the light separating unit 13 and irradiates the retina 74 with the light. As a result, the optical system from the light source 11 to the light splitting unit 13 can be shared by the visible laser beam 50a and the infrared laser beam 50b, so that the number of parts can be reduced and the inspection apparatus can be miniaturized.

From the viewpoint of miniaturizing the inspection apparatus, the light separating unit 13 is preferably a dichroic mirror that transmits the visible laser light 50a and reflects the infrared laser light 50b. The light separating unit 13 may be a dichroic mirror that reflects the visible laser light 50a and transmits the infrared laser light 50b. Even in this case, the inspection device can be miniaturized.

Further, according to the first embodiment, as illustrated in FIG. 2, the combining unit 26 that combines the visible laser beam 50 a scanned by the scanning unit 20 and the infrared laser beam 50 b scanned by the scanning unit 22 is provided. Thereby, it is possible to easily realize that the optical axes of the visible laser light 50a and the infrared laser light 50b are aligned and projected on the retina 74.

FIG. 6 is a block diagram of a visual inspection apparatus according to a second embodiment. As shown in FIG. 6, the visual inspection apparatus 200 of the second embodiment further includes an input unit 42 as compared with the visual inspection apparatus 100 of the first embodiment. The input unit 42 is a device through which the subject inputs a result, and is, for example, a button, a touch panel, a keyboard, and / or a mouse. The signal processing unit 32 processes the output signal of the detector 40 and the output signal of the input unit 42 based on the control signal from the drive control unit 31. The detector 40 and the signal processing unit 32 start detection based on the synchronization signal from the drive circuit 16 at the timing when the light source 11 emits the visible laser light 50 a and the infrared laser light 50 b. The other configuration is the same as that of the first embodiment shown in FIG. The optical system of the visual inspection apparatus 200 of the second embodiment is the same as that of the first embodiment shown in FIG.

FIG. 7 is an example of an image projected onto the retina in the second embodiment. In the second embodiment, an image 60 a as shown in FIG. 7 is projected on the retina 74. That is, in addition to the fixation visual target 63 projected on the central region of the retina 74, the inspection visual target 65 for inspecting the eye 70 is projected. Although the test target 65 is projected at different times on different regions of the retina 74, FIG. 7 illustrates all of the test target 65 projected on the retina 74 for convenience. The test target 65 is, for example, stimulation light irradiated to a region of a predetermined size. Although the case of a circular shape will be described as an example of the shape of the test target 65, it may be a polygonal shape such as an elliptical shape or a quadrangular shape. The inspection target 65 may be white light including red, green and blue laser light, or may be monochromatic light including laser light of a single wavelength. The diameter of the test target 65 is, for example, about several μm.

FIG. 8 is a flowchart showing processing in the second embodiment. As shown in FIG. 8, the control unit 30 projects an image 60 a as shown in FIG. 7 onto the retina 74 and performs an examination using the examination target 65 (step S <b> 30).

FIG. 9 is a flowchart showing a method of examination (step S30 in FIG. 8) using the examination target in the second embodiment. 10 (a) to 10 (d) are diagrams for explaining an examination using an examination target. As illustrated in FIG. 9, the drive control unit 31 generates an image 60 a as illustrated in FIG. 7, and causes the projection unit 10 to project the generated image 60 a to set the fixation target 63 and the inspection target 65 on the retina 74. Project (step S50). As described in FIG. 7, the test target 65 is projected at different times to different areas of the retina 74. Therefore, as shown in FIG. 10A, the inspection target 65 a of the inspection targets projected onto different regions of the retina 74 is projected.

Returning to FIG. 9, the signal processing unit 32 acquires the output signal of the input unit 42 (step S52). The subject operates the input unit 42 when recognizing that the test target 65 a is projected on the retina 74. When the subject operates the input unit 42, an output signal is output from the input unit 42 to the signal processing unit 32. The signal processing unit 32 starts acquiring the output signal of the input unit 42 in synchronization with the emission of the visible laser light 50 a.

Next, the drive control unit 31 determines whether the projection of all the test target 65 has been completed on the retina 74 (step S54). If the examination mark 65 to be projected still remains, the determination at step S54 is negative (step S54: No), and steps S50 and S52 are repeated. By repeatedly performing steps S50 and S52, for example, several seconds after projecting the test target 65a of FIG. 10A, the test target in another region of the retina 74 as shown in FIG. 10B. After 65b has been projected and several seconds have elapsed, as shown in FIG. 10 (c), the inspection target 65c is projected onto a further area of the retina 74. This is repeated, and the last examination target 65z is projected on the retina 74 as shown in FIG. 10 (d). When the projection of all the inspection marks 65 is completed (step S54: Yes), the inspection using the inspection marks 65 is ended. This allows, for example, inspection of visual field defects.

Returning to FIG. 8, the control unit 30 detects the state of the fundus using the infrared laser light 50b (step S32). The detection of the state of the fundus oculi using the infrared laser light 50b is performed in the processes of steps S10 to S18 in FIG.

Next, the image generation unit 33 generates a visual field defect image based on the output signal of the input unit 42 acquired by the signal processing unit 32 in the examination using the inspection visual target 65. The image generation unit 33 generates a fundus oculi image based on the output signal of the detector 40 acquired by the signal processing unit 32 (in the inspection using the infrared laser light 50b) by being irradiated with the infrared laser light 50b. Then, the image generation unit 33 generates a superimposed image in which the visual field loss image and the fundus image are superimposed (step S34). The display unit 41 displays the superimposed image (step S36). The examiner examines the vision of the subject by the examiner examining the examination image superimposed and displayed on the display unit 41.

FIGS. 11A to 11C are examples of the fundus image, the visual field defect image, and the superimposed image generated by the image generation unit. FIG. 11A is a fundus image. As in FIG. 5, reference numeral 80 is a fovea, reference numeral 81 is an optic nerve head, and reference numeral 82 is a retinal artery or retinal vein. In addition, a lesion 83 is shown by a cross hatch. FIG. 11 (b) is a visual field defect image. A portion 66 where the subject does not respond to the input section 42 despite projecting the test target 65 onto the retina 74 is indicated by a dotted line. FIG. 11C shows a superimposed image in which the fundus oculi image and the visual field defect image are superimposed. By superimposing the fundus oculi image and the visual field defect image, it is possible to evaluate the relationship between the lesion 83 in the fundus image and the portion 66 of the visual field defect in the visual field defect image.

According to the second embodiment, the control unit 30 controls the emission of the visible laser light 50a from the light source 11 to project the test target 65 for testing the eye 70 on the retina 74 of the subject. Thereby, in addition to the detection of the state of the fundus of the eye 70 using the infrared laser light 50b, the examination of the eye 70 using the visible laser light 50a can also be performed.

Although in FIG. 8 the inspection using the inspection target 65 is performed and then the inspection using the infrared laser light 50b is performed, the inspection target 65 is used after the inspection using the infrared laser light 50b. The examination used may be performed. In this case, when an inspection using the inspection target 65 is performed, the visible laser light 50a is emitted from the light source 11 and the scanning unit 20 is driven, and the infrared laser light 50b is not emitted from the light source 11 and The scanning unit 22 may not be driven. When an inspection using the infrared laser beam 50b is performed, the infrared laser beam 50b is emitted from the light source 11 and the scanning unit 22 is driven, and the visible laser beam 50a is not emitted from the light source 11, and the scanning unit 20 may not be driven. Further, the inspection using the inspection target 65 and the inspection using the infrared laser light 50b may be performed in parallel. That is, the control unit 30 may simultaneously perform the projection of the inspection target 65 and the irradiation of the infrared laser light 50b in parallel. Thereby, shortening of inspection time can be aimed at.

Further, according to the second embodiment, as shown in FIG. 11C, the control unit 30 generates the inspection image (fundus oculi image) generated based on the output signal of the detector 40 and the output signal of the input unit 42. A superimposed image is generated by superimposing the test image (image relating to visual field loss). Thereby, the relationship between the lesion area of the examination image of the examination with the visible laser beam 50a and the lesion area of the examination image of the examination with the infrared laser beam 50b can be evaluated. It can also contribute to early detection of onset of diabetes, early detection of glaucoma, and / or early detection of age-related macular degeneration. Note that, by generating an image related to visual field loss, it is possible to specify PRL (Preferred Retinal Locus: another retinal region where a visual target has come to be captured instead because the sensitivity of the retinal fovea has decreased). .

In the second embodiment, the examination image generated based on the output signal of the detector 40 is a fundus image, and the examination image generated based on the output signal of the input unit 42 is an image related to visual field loss. In the case of FIGS. 12 (a) and 12 (b) are other examples of images projected onto the retina in Example 2. FIG. As shown in FIGS. 12 (a) and 12 (b), an image 60b having a test target 67 for examining retinal visual acuity may be projected onto the retina 74. That is, based on the output signal of the input unit 42, an image of a test result of retinal visual acuity may be generated. As shown in FIG. 12A, the inspection target 67 is projected on the center of the image 60b, and a plurality of dot patterns are projected as the fixation target 63 so as to surround the inspection target 67. As a result, when the subject looks at the plurality of fixation targets 63 uniformly, the inspection target 67 is projected to the center of the retina 74. As shown in FIG. 12B, the fixation visual target 63 is projected to the center of the image 60b, and the inspection visual target 67 is projected to the periphery. As described in FIG. 7, the test target 67 is projected to different regions of the retina 74 at different times, but here, for convenience, all of the test target 67 projected onto the retina 74 Is illustrated. As a result, when the subject looks at the fixation target 63, the inspection target 67 is projected to a desired position of the retina 74. As described above, when projecting the test target 67, the test target 67 is placed at a desired position on the retina 74 by projecting the fixation target 63 and causing the subject to fixate the fixation target 63. It can be projected. The inspection target 67 is not limited to the case of the Landolt ring, and may be other cases such as characters.

In the first and second embodiments, the image projection optical system 14 projects the fixation target 63 and the infrared light optical system 15 irradiates the retina 74 with the infrared laser light 50 b, so that the control unit 30 is red. An image in which the fixation visual target 63 is displayed on the inspection image of the eye 70 by the external laser beam 50 b can be acquired. In this way, when inspection images of a plurality of frames are acquired, alignment of the image can be easily performed by the fixation visual target 63 on the inspection image, and even though the fixation visual target is projected, Even when the line of sight of the examiner moves, superposition of inspection images of a plurality of frames, identification of the position of a lesion, and the like can be performed more accurately.

In Example 1 and Example 2, the image projection optical system 14 projects an image such as a visual target, and the infrared light optical system 15 irradiates the retina 74 with the fundus of the eye 70 of the subject 70 by the infrared laser light 50b. An example of detecting the state of In the third embodiment, the case where the image projection optical system 14 detects the state of the fundus of the eye 70 of the subject also by the visible laser light 50 a emitted to the retina 74 will be described.

The block diagram and the optical system of the visual inspection apparatus according to the third embodiment are the same as FIGS. 1 and 2 of the first embodiment, and therefore will be described using FIGS. 1 and 2 of the first embodiment. The visual inspection apparatus of the third embodiment is different from the first embodiment in that the detector 40 is a photodetector capable of detecting visible light to infrared light. Therefore, in the third embodiment, the image projection optical system 14 irradiates the retina 74 and the detector 40 can detect the visible laser light 50 a reflected by the retina 74. The visible laser beam 50a reflected by the retina 74 returns in the optical path along which the visible laser beam 50a has traveled toward the retina 74 in the order of the lens 27, the combining unit 26, the lens 25, the scanning unit 20, the flat mirror 21, and the light separating unit 13. , And incident on the detector 40 through the half mirror 43 and the lens 44.

FIG. 13 is a flowchart showing the process in the third embodiment. As illustrated in FIG. 13, the drive control unit 31 causes the projection unit 10 to irradiate the visible laser light 50 a onto the retina 74 (step S <b> 60). Next, the signal processing unit 32 acquires an output signal of the detector 40 (step S62). For example, the detector 40 detects the visible laser light 50 a in synchronization with the synchronization signal from the drive circuit 16. That is, the detector 40 detects the visible laser light 50 a in synchronization with the emission of the visible laser light 50 a from the light source 11. The signal processing unit 32 starts acquiring the output signal of the detector 40 in synchronization with the emission of the visible laser light 50a.

Next, the drive control unit 31 causes the projection unit 10 to irradiate the retina 74 with the infrared laser light 50b instead of the visible laser light 50a (step S64). Next, the signal processing unit 32 acquires an output signal of the detector 40 (step S66). For example, the detector 40 detects the infrared laser light 50 b in synchronization with the synchronization signal from the drive circuit 16. That is, the detector 40 detects the infrared laser light 50 b in synchronization with the emission of the infrared laser light 50 b from the light source 11. The signal processing unit 32 starts acquiring the output signal of the detector 40 in synchronization with the emission of the infrared laser light 50 b.

Next, the drive control unit 31 determines whether or not the irradiation of the visible laser light 50a and the infrared laser light 50b has ended in a predetermined number of frames (step S68). The predetermined number of frames may be one frame or a plurality of frames such as five or ten frames.

When the irradiation of the predetermined number of frames is not completed (step S68: No), steps S60 to S66 are repeated. When the irradiation of the predetermined number of frames is completed (Step S68: Yes), the image generation unit 33 generates an inspection image of the eye 70 based on the output signal of the detector 40 acquired by the signal processing unit 32 (Step S70). . For example, the image generation unit 33 generates a first examination image (first fundus image) based on the output signal of the detector 40 by the visible laser light 50a reflected by the retina 74, and the infrared laser light 50b reflected by the retina 74 A second examination image (second fundus image) is generated based on the output signal of the detector 40 according to The display unit 41 displays an examination image (step S72). The doctor examines the inspection image displayed on the display unit 41 and examines the vision of the subject.

According to the third embodiment, in addition to detecting the state of the fundus of the eye 70 from the output signal based on the infrared laser light 50 b of the detector 40, the control unit 30 also outputs the output based on the visible laser light 50 a of the detector 40 The state of the fundus of the eye 70 is detected from the signal. The two fundus states detected are based on laser beams of different frequencies, so that the states of the fundus with different characteristics can be detected. As a result, it is possible to evaluate different fundus conditions and improve the accuracy of visual inspection.

In the third embodiment, as an example of detecting the state of the fundus of the eye 70 from the output signal based on the visible laser light 50a and the infrared laser light 50b of the detector 40, the case of acquiring the fundus image of the eye 70 is shown. Other cases are also possible.

Also in the third embodiment, the control unit 30 may project a fixation target for causing the subject's gaze to be directed to the retina 74 of the subject as in the first embodiment, and / or As in the second embodiment, a test target for testing the eye 70 of the subject may be projected onto the retina 74 of the subject.

In the first to third embodiments, when the visible laser light 50a and the infrared laser light 50b are two-dimensionally scanned by the

separate scanning units

20 and 22, that is, the scanning unit 20 that scans the visible laser light 50a and the red Although the case where it has two types of scanning parts with the scanning part 22 which scans the external laser beam 50b was shown as an example, in Example 4, the case where it scans in two dimensions by one scanning part is demonstrated. That is, in the first to third embodiments, the image projection optical system 14 having the scanning unit 20 for scanning the visible laser light 50a of visible light and the infrared light having the scanning unit 22 for scanning the infrared laser light 50b of invisible light The case of including the optical system 15 has been described as an example. On the other hand, in the fourth embodiment, an optical system for visible light and invisible light is made common, and a case where both a laser light of visible light and a laser light of invisible light are scanned by one scanning unit will be described.

FIG. 14 is a block diagram of a visual inspection apparatus according to a fourth embodiment. As illustrated in FIG. 14, in the visual inspection apparatus 300 according to the fourth embodiment, the projection unit 10a includes a visible light source 90, a visible light adjustment unit 91, an invisible light source 92, an invisible light adjustment unit 93, a light source light combining unit 94, and a scanning unit 20, a drive circuit 16 and an input circuit 17. The drive circuit 16 drives the visible light source 90, the invisible light source 92, and the scanning unit 20 based on the image signal acquired by the input circuit 17 and the control signal of the drive control unit 31. The other configuration is the same as that of the first embodiment shown in FIG. Also in the visual inspection apparatus 300 of the fourth embodiment, as in FIG. 6 of the second embodiment, the input unit 42 may be provided.

FIG. 15 is a diagram of an optical system of a visual inspection apparatus according to a fourth embodiment. As illustrated in FIG. 15, the visual inspection apparatus 300 of the fourth embodiment includes a visible light source 90, a visible light adjustment unit 91, an invisible light source 92, an invisible light adjustment unit 93, and a light source light synthesis unit 94. In the fourth embodiment, similarly to the first embodiment, laser light is irradiated to the retina 74 of the subject using Maxwell vision. The visible light source 90 emits visible laser light 51a of red laser light, green laser light, and blue laser light, and the optical axes of the laser lights of the respective wavelengths coincide with each other. The visible light adjustment unit 91 has a collimating lens, a toric lens, and / or an aperture, etc., which has a characteristic that rivals visible light, and the visible laser light 51a has a suitable numerical aperture (NA) and / or beam diameter. Adjusted to The visible laser beam 51a is a light beam in which a red laser beam, a green laser beam, and a blue laser beam are combined, and the optical axes of the respective laser beams coincide with each other.

The invisible light source 92 emits invisible laser light 51 b such as infrared light. The invisible light adjusting unit 93 includes a collimating lens, a toric lens, and / or an aperture having characteristics suitable for invisible light such as infrared light, and the invisible laser light 51 b has a suitable numerical aperture (NA) and / or Or it is adjusted to the beam diameter.

The light source light synthesis unit 94 reflects the visible laser light 51a adjusted by the visible light adjustment unit 91, and transmits the invisible laser light 51b adjusted by the invisible light adjustment unit 93, thereby adjusting the visible laser light 51a. It is a dichroic mirror that generates a combined laser beam 53 in which the adjusted invisible laser beam 51b is combined. The light source light combining unit 94 is not limited to a dichroic mirror, and may be another optical element such as a dichroic prism.

The combined laser beam 53 passes through the half mirror 43, is reflected by the plane mirror 21, and is two-dimensionally scanned by the scanning unit 20. Here, as in the first embodiment, the scanning unit 20 vibrates at a relatively high frequency such as 28 kHz so that an image of 60 frames is projected per second. The combined laser beam 53 scanned by the scanning unit 20 converges in the vicinity of the lens 72 through the lens 25 and the lens 27, passes through the vitreous body 76, and irradiates the retina 74. The lens 25 and the lens 27 irradiate the visible laser light 51a of the retina 74 of the subject to project an image on the retina 74 of the subject, and serve as an irradiation optical system 95 which irradiates the invisible laser light 51b to the retina 74 of the subject.
Since the synthetic laser beam 53 is a laser beam obtained by mixing the visible laser beam 51a and the invisible laser beam 51b, in the fourth embodiment, the visible laser beam 51a and the invisible laser beam 51b are applied to the retina 74 at the same scanning frequency. It is simultaneously irradiated to the same position.

The synthetic laser light 53 applied to the retina 74 is reflected by the retina 74. The reflected combined laser light 53 returns in the optical path along which the combined laser light 53 has traveled to the retina 74. That is, the reflected combined laser light 53 returns in the optical path in which the combined laser light 53 has traveled toward the retina 74 in the order of the lens 27, the lens 25, the scanning unit 20 and the flat mirror 21. The returned combined laser beam 53 is reflected by the half mirror 43 in the direction of the lens 44 and enters the detector 40 through the lens 44. The detector 40 has a characteristic of detecting invisible light and not detecting visible light, and therefore detects only the reflected invisible laser light 51b. The detection of the state of the fundus of the eye 70 (acquisition of state information of the fundus) can be performed based on the detection result such as the luminance change of the invisible laser beam 51b by the detector 40, and a fundus image is acquired as an example of the detection target. be able to. Here, if the detector 40 has a characteristic capable of detecting both visible light and invisible light, the detection result detected by the detector 40 is matched with the irradiation timing of the visible laser light 51a and the invisible laser light 51b. If referred to, detection of both the visible laser light 51a and the invisible laser light 51b is also possible.

In Examples 1 to 3, the method of scanning and projecting the visible laser light and the invisible laser light described in FIGS. 3, 7, 10, and 12 and FIGS. 4, 8, 9, and Regarding the process control flow described in 13, the method of scanning and projection in the fourth embodiment and the control flow in the fourth embodiment by replacing the visible laser light 50a and the infrared laser light 50b with the visible laser light 51a and the invisible laser light 51b. It will be explained.

According to the fourth embodiment, the combined laser beam 53 in which the visible laser beam 51a and the invisible laser beam 51b are combined by the light source light combining unit 94 is scanned by one scanning unit 20 and is applied to the retina 74 of the subject. As described above, since the scanning unit 20 that scans the visible laser light 51a and the invisible laser light 51b is made common, control of the scanning unit 20 is simplified, and simplification of the apparatus is also realized. it can.

In the first to fourth embodiments, the case of infrared rays as the invisible light is shown as an example, but other cases such as ultraviolet rays may be used. Although the case where the wavelength of the infrared ray is about 850 nm is shown as an example, it may be the case of near infrared rays of other wavelengths, or it may be the case of middle infrared rays or far infrared rays.

As mentioned above, although the embodiment of the present invention has been described in detail, the present invention is not limited to such a specific embodiment, and various modifications may be made within the scope of the subject matter of the present invention described in the claims. Changes are possible.

10, 10a Projection unit 11 Light source 12 Adjustment unit 13 Spectroscopic unit 14 Image projection optical system 15 Infrared light optical system 16 Drive circuit 17

Input circuit

20, 22

Scanning unit

21, 23

Flat mirror

24, 25, 27 Lens 26 Combining unit 30 Control unit 31 Drive control unit 32 Signal processing unit 33 Image generation unit 40 Detector 41 Display unit 42 Input unit 43 Half mirror 44 Lens 50 Laser light 50a Visible laser light 50b Infrared laser light 51a Visible laser light 51b Invisible laser light 53 Composition Laser beam 60-60b Image 63 Fixation target 65-65z Test target 66 Part 67 Test target 70 Eye 72 Lens 74 Retina 76 Vitreous body 80 Central fossa 81 Optic papilla 82 Retinal artery or retinal vein 83 Lesion part 90 Visible light Light source 91 visible light adjustment unit 92 invisible light source 93 invisible light adjustment unit 9 DESCRIPTION OF SYMBOLS 4 Light source light-synthesis part 95 Irradiation

optical system

100, 200, 300 Visual inspection apparatus

Claims

A light source that emits visible light and invisible light;
An image having a first scanning unit for two-dimensionally scanning the visible light by oscillating at a first frequency, and projecting the image on the retina of the subject by irradiating the visible light to the retina of the subject Projection optics,
An invisible light optical system including a second scanning unit configured to two-dimensionally scan the invisible light by vibrating at a second frequency different from the first frequency, and irradiating the invisible light to the retina of the subject;
A detector for detecting the invisible light reflected by the retina of the subject;
A control unit configured to control emission of the visible light beam and the invisible light beam from the light source and to detect a state of a fundus of the subject from an output signal of the detector.
The light source may further include a splitting unit that emits the visible light emitted from the light source in a first direction and emits the invisible light in a second direction different from the first direction.
The optical axes of the image projection optical system and the invisible light optical system coincide with each other,
The image projection optical system two-dimensionally scans the visible light emitted in the first direction and irradiates the retina of the subject.
The visual inspection apparatus according to claim 1, wherein the invisible light optical system two-dimensionally scans the invisible light emitted in the second direction to irradiate the retina of the subject.
The visual inspection apparatus according to claim 2, wherein the light splitting unit is a dichroic mirror that transmits one of the visible light and the invisible light and reflects the other.
The visual inspection apparatus according to any one of claims 1 to 3, further comprising: a combining unit configured to combine the visible light scanned by the first scanning unit and the invisible light scanned by the second scanning unit.
The invisible rays are infrared rays,
The visual inspection apparatus according to any one of claims 1 to 4, wherein the control unit generates a fundus image of the eye of the subject based on an output signal of the detector.
The control unit controls the emission of the visible light from the light source to project a fixation target for directing the line of sight of the subject to the retina of the subject, and the invisible light from the light source The visual inspection apparatus according to any one of claims 1 to 5, wherein the invisible light is emitted to the retina of the subject.
7. The control unit projects an examination target for inspecting the eye of the subject on the retina of the subject by controlling the emission of the visible light from the light source. A visual inspection apparatus according to any one of the preceding claims.
The control unit controls emission of the visible light from the light source to project a test target for testing the eye of the subject onto the retina of the subject, and the invisible light from the light source The visual inspection apparatus according to any one of claims 1 to 7, wherein the irradiation of the invisible light to the retina of the subject is performed in parallel.
The control unit controls emission of the visible light from the light source to project a test target for testing the eye of the subject on the retina of the subject, and outputs the test signal to the output signal of the detector. The third inspection image is generated by superimposing the first inspection image generated based on the second inspection image generated based on the response input according to the test target of the subject. The visual inspection apparatus according to any one of the preceding claims.
The visual inspection apparatus according to claim 9, wherein the first inspection image is a fundus image, and the second inspection image is an image regarding a visual field defect.
A light source that emits visible light and invisible light;
An image having a first scanning unit for two-dimensionally scanning the visible light by oscillating at a first frequency, and projecting the image on the retina of the subject by irradiating the visible light to the retina of the subject Projection optics,
An invisible light optical system including a second scanning unit configured to two-dimensionally scan the invisible light by vibrating at a second frequency different from the first frequency, and irradiating the invisible light to the retina of the subject;
A detector for detecting the visible light and the invisible light reflected by the retina of the subject;
Control of emission of the visible light and the invisible light from the light source and detection of a state of a first fundus of the subject from an output signal based on the visible light of the detector and the invisible of the detector A control unit configured to detect a state of a second fundus of the subject from an output signal based on a light beam.
The control unit controls emission of the visible light from the light source to inspect a fixation target for causing the subject's gaze to point at the retina of the subject and an eye of the subject. The visual inspection apparatus according to claim 11, wherein at least one of the inspection targets to be projected is projected.
The visual inspection apparatus according to claim 11, wherein the control unit acquires a fundus image of the eye of the subject as the detection of the state of the first fundus and the detection of the state of the second fundus.
A visible light source that emits visible light;
An invisible light source that emits invisible light;
A light source light combining unit that combines the visible light and the invisible light to generate combined light;
A scanning unit that two-dimensionally scans the visible light beam and the invisible light beam;
An irradiation optical system which irradiates the visible light onto the retina of the subject to project an image on the retina of the subject and irradiates the invisible light onto the retina of the subject;
A detector for detecting the invisible light reflected by the retina of the subject;
A control unit configured to control emission of the visible light from the visible light source and the invisible light from the invisible light source and to detect the state of the fundus of the subject from the output signal of the detector; Visual inspection apparatus provided.
The invisible rays are infrared rays,
The visual inspection apparatus according to claim 14, wherein the control unit generates a fundus image of the eye of the subject based on an output signal of the detector.
The control unit controls the emission of the visible light from the visible light source to project a fixation target for directing the line of sight of the subject on the retina of the subject, and the invisible light source The visual inspection apparatus according to claim 14 or 15, wherein the invisible light is emitted from the light source to irradiate the retina of the subject with the invisible light.
The control unit projects an examination target for examining an eye of the subject on the retina of the subject by controlling emission of the visible light from the visible light source. The visual inspection apparatus according to any one of the preceding claims.
The control unit controls the emission of the visible light from the visible light source to project a test target for testing the eye of the subject on the retina of the subject, and the output of the detector A third inspection image is generated by superimposing a first inspection image generated based on a signal and a second inspection image generated based on a response input according to the test target of the subject. A visual inspection apparatus according to any of the preceding claims.
The visual inspection apparatus according to claim 18, wherein the first inspection image is a fundus image, and the second inspection image is an image regarding a visual field defect.